Just as title case looks more formal and serious, sentence case looks more casual and friendly. I’m a writer at Dropbox, and we intentionally write in sentence case because we want our brand to feel natural and approachable. We think our product’s voice sets us apart from our competitors, and using sentence case is one way for us to maintain that voice.
Yeah, right… Not sure who fed you guys that crap but it’s heaps of bullshit if you ask me. People really don’t care about that as long as the product works.